US20150103565A1 - Dc-to-dc converter - Google Patents
Dc-to-dc converter Download PDFInfo
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- US20150103565A1 US20150103565A1 US14/510,524 US201414510524A US2015103565A1 US 20150103565 A1 US20150103565 A1 US 20150103565A1 US 201414510524 A US201414510524 A US 201414510524A US 2015103565 A1 US2015103565 A1 US 2015103565A1
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- frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33573—Full-bridge at primary side of an isolation transformer
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33538—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0032—Control circuits allowing low power mode operation, e.g. in standby mode
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Definitions
- FIG. 4A is an internal-circuit block diagram of a PWM-control drive circuit
- the oscillator 250 outputs an oscillation signal having a frequency corresponding to the resistance value of the oscillation resistor 251 and the capacitance value of the oscillation capacitor 252 .
- the resistance value of the oscillation resistor 251 is indicated by R T [k ⁇ ]
- the capacitance value of the oscillation capacitor 252 is indicated by C T [ ⁇ F]
- the oscillation frequency f OSC [kHz] of the oscillator 250 is given by:
- the fall time T f of the voltage at the gate of the switch 422 increases according to the time constant ⁇ f .
- the length of a region (indicated by an arrow D in FIG. 8B ) in which the switch 422 performs an active operation increases, and the switch 422 is turned off gradually.
- the oscillation frequency f OSC changes gradually from 100 [kHz] to 80 [kHz].
- step S 101 the variable resistor driver 621 obtains, from the load-current detector 320 , the current value of load current.
- step S 102 the variable resistor driver 621 compares the magnitude of the obtained load current with a threshold. If the variable resistor driver 621 determines that the magnitude of the obtained load current is larger than the threshold, the process proceeds to step S 103 . If the variable resistor driver 621 determines that the magnitude of the obtained load current is not larger than the threshold, the process proceeds to step S 105 .
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
A direct current to direct current converter includes: a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side; a switch configured to periodically switch the voltage applied to the first side of the transformer; a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and a switching-frequency switching circuit configured to switch, when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch, when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.
Description
- This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-214968, filed on Oct. 15, 2013, the entire contents of which are incorporated herein by reference.
- The embodiments discussed herein are related to a direct current to direct current (DC-to-DC) converter.
- In DC-to-DC converters used for power-supply devices and so on, a variety of technologies for improving the power conversion efficiencies have been disclosed in order to deal with energy saving regulations in recent years.
- For example, there has been a known switching power-supply device including a rectifier circuit, a switching element, a power converter, a detector, and a control circuit. The rectifier circuit converts power from an alternating-current power supply into direct-current power, and the switching element intermittently switches on the direct-current power, obtained from the rectifier circuit, via a primary winding of a transformer. The power converter has a secondary winding and a tertiary winding that induce power corresponding to the power supplied to the primary winding of the transformer via the intermittent switching of the switching element. The power converter rectifies and smooths the power output from the secondary winding and supplies the resulting power to a load circuit at the secondary side. The detector is driven by power obtained by rectifying and smoothing the power obtained from the tertiary winding, to detect the power supplied from the secondary winding to the load circuit, in order to control the power so as to obtain a predetermined voltage and a predetermined current. The control circuit controls the on period of the switching element so that the power supplied to the secondary side reaches a predetermined value, based on a signal detected by the detector. In the above-described switching power-supply device, in a mode in which equipment serving as the load circuit coupled to an output of the secondary side operates, the switching element is subjected to pulse width modulation (PWM) control with a certain fundamental frequency, and in a mode in which the operation of the equipment stops, the fundamental frequency is controlled so as to shift to a lower frequency. The control circuit performs control so that, during the PWM control with the fundamental frequency in the equipment operation mode, the on time of the switching element reaches a minimum pulse duration when the output power decreases. Also, when the fundamental frequency shifts to the lower frequency in the equipment stop mode and the frequency decreases, the control circuit performs control so that the minimum on-pulse duration increases gradually in conjunction with the reduction in the frequency. The minimum on-pulse duration of the switching element is controlled so as to increase when a voltage of the alternating-current power is low, and the on-pulse duration of the switching element is controlled so as to decrease when the voltage of the alternating-current power is high.
- There is also a known switching power supply that includes a transformer, a secondary direct-current power supply, a constant-voltage control circuit, a switching-power-supply-control integrated circuit, startup resistors, a feedback direct-current power supply, a switching element, and a switching-frequency switching circuit. The transformer has a primary winding, a secondary winding, and a feedback winding. The secondary direct-current power supply rectifies and smooths an output of the secondary winding, the constant-voltage control circuit is coupled to the secondary direct-current power supply, and a feedback control circuit maintains an output voltage. The feedback direct-current power supply rectifies and smooths the output of the feedback winding. The switching-power-supply-control integrated circuit has at least a power-supply voltage terminal, a ground terminal, an oscillation control terminal, a current limit terminal, a feedback terminal, and an oscillation-constant terminal. The startup resistors are coupled between a power-supply voltage terminal of the switching-power-supply-control integrated circuit and an input voltage terminal, and the feedback direct-current power supply is coupled to the power-supply voltage terminal of the switching-power-supply-control integrated circuit. The switching element is coupled to the input voltage terminal via the primary winding and has an oscillation frequency controlled in accordance with an oscillation-control terminal voltage of the integrated circuit. The switching-frequency switching circuit is coupled to the oscillation-constant terminal to reduce the oscillation frequency of the switching element when the load power is reduced or when there is no load.
- The followings are reference documents:
- [Document 1] Japanese Laid-open Patent Publication No. 2004-304885 and
- [Document 2] Japanese Laid-open Patent Publication No. 9-117134.
- According to an aspect of the invention, a direct current to direct current converter includes: a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side; a switch configured to periodically switch the voltage applied to the first side of the transformer; a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and a switching-frequency switching circuit configured to switch, when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch, when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.
- The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
- It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
-
FIG. 1 is a circuit block diagram of a DC-to-DC converter in related art; -
FIG. 2A is an internal-circuit block diagram of a PWM-control drive circuit; -
FIG. 2B is a timing chart of the PWM-control drive circuit; -
FIG. 3 is a circuit block diagram of a DC-to-DC converter according to a first embodiment; -
FIG. 4A is an internal-circuit block diagram of a PWM-control drive circuit; -
FIG. 4B is a circuit block diagram depicting a coupling relationship between the PWM-control drive circuit and a switching-frequency switching circuit; -
FIG. 5 is a timing chart of the DC-to-DC converter illustrated inFIG. 3 ; -
FIG. 6A is a timing chart illustrating switching of the oscillation frequency of an oscillator; -
FIG. 6B illustrates a B-H curve of a transformer which corresponds toFIG. 6A ; -
FIG. 7 is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a second embodiment; -
FIG. 8A is a timing chart of the DC-to-DC converter illustrated inFIG. 7 ; -
FIG. 8B is a partially enlarged chart of a portion denoted by a dashed-line ellipse A inFIG. 8A ; -
FIG. 8C is a partially enlarged chart of a portion denoted by a dashed-line ellipse B inFIG. 8A ; -
FIG. 9A is a timing chart illustrating switching of the oscillation frequency of an oscillator in the DC-to-DC converter illustrated inFIG. 7 ; -
FIG. 9B illustrates a B-H curve of the transformer which corresponds toFIG. 9A ; -
FIG. 10 is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a third embodiment; -
FIG. 11A is a timing chart of the DC-to-DC converter illustrated inFIG. 10 ; -
FIG. 11B is a partially enlarged chart of a portion indicated by a dashed-line ellipse A inFIG. 11A ; -
FIG. 11C is a partially enlarged chart of a portion indicated by a dashed-line ellipse B inFIG. 11A ; -
FIG. 12A is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a fourth embodiment; -
FIG. 12B is an internal circuit block diagram of a variable resistor inFIG. 12A ; -
FIG. 13 is a flowchart illustrating an example of processing executed by the variable resistor driver in the DC-to-DC converter; -
FIG. 14 is a flowchart illustrating another example of processing executed by the variable resistor driver in the DC-to-DC converter; and -
FIG. 15 is a flowchart illustrating yet another example of the processing executed by the variable resistor driver in the DC-to-DC converter. - A DC-to-DC converter according to the present disclosure will be described below with reference to the accompanying drawings. However, the technical scope of the present disclosure is not limited to embodiments thereof.
- Before a description is given of the DC-to-DC converter according to the embodiments, the DC-to-DC converter in related art will be described in more detail.
-
FIG. 1 is a circuit block diagram of the DC-to-DC converter in the related art. - A DC-to-
DC converter 100 includes atransformer 10, afirst switch 11, asecond switch 12, athird switch 13, afourth switch 14, afirst diode 21, asecond diode 22, afirst reactance element 23, and asecond reactance element 24. The DC-to-DC converter 100 further includes a PWM-control drive circuit 25, afirst capacitor 26, and asecond capacitor 27. - The
transformer 10 has a primary winding to which a rectangular wave is applied and a secondary winding that outputs a voltage resulting from reduction of a voltage applied to the primary winding. Thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 are n-type metal oxide semiconductor (nMOS) transistors and switch the voltage applied to the primary winding of thetransformer 10. - A first output terminal OUTPUT1 of the PWM-
control drive circuit 25 is coupled to gates of thefirst switch 11 and thefourth switch 14, and a second output terminal OUTPUT2 of the PWM-control drive circuit 25 is coupled to gates of thesecond switch 12 and thethird switch 13. Drains of thefirst switch 11 and thesecond switch 12 are coupled to a positive terminal of a direct-current power supply, and sources of thethird switch 13 and thefourth switch 14 are coupled to a negative terminal of the direct-current power supply. A source of thefirst switch 11 and a drain of thethird switch 13 are coupled to one terminal of the primary winding of thetransformer 10, and a source of thesecond switch 12 and a drain of thefourth switch 14 are coupled to another terminal of the primary winding of thetransformer 10. - The
first switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 are put into three switching states, namely, first to third switching states, based on signals output from the first output terminal OUTPUT1 and the second output terminal OUTPUT2 of the PWM-control drive circuit 25. The first switch state is a state in which thefirst switch 11 and thefourth switch 14 are turned on, thesecond switch 12 and thethird switch 13 are turned off, and a positive voltage is applied to the primary winding of thetransformer 10. The second switch state is a state in which thefirst switch 11 and thefourth switch 14 are turned off, thesecond switch 12 and thethird switch 13 are turned on, and a negative voltage is applied to the primary winding of thetransformer 10. The third switch state is a state in which thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 are all turned off. In the third switch state, current flows via thefirst diode 21 or thesecond diode 22, and voltages in the primary winding and the secondary winding of thetransformer 10 become zero, so that a magnetic flux density in thetransformer 10 is maintained. For example, when thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 change from the first switch state to the third switch state, the magnetic flux density in thetransformer 10 is maintained at the last magnetic flux density in the first switch state. When thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 change from the second switch state to the third switch state, the magnetic flux density in thetransformer 10 is maintained at the last magnetic flux density in the second switch state. -
FIG. 2A is an internal-circuit block diagram of the PWM-control drive circuit 25, andFIG. 2B is a timing chart of the PWM-control drive circuit 25. - The PWM-
control drive circuit 25 includes anoscillator 250, anoscillation resistor 251, anoscillation capacitor 252, acomparator 253, aninversion element 254, and a T flip-flop 255. The PWM-control drive circuit 25 further includes a first ANDelement 256 a, a second ANDelement 256 b, a first NORelement 257 a, and a second NORelement 257 b. The PWM-control drive circuit 25 further includes afirst transistor 258 a, asecond transistor 258 b, afirst output resistor 259 a, and asecond output resistor 259 b. - The
oscillator 250 outputs an oscillation signal having a frequency corresponding to the resistance value of theoscillation resistor 251 and the capacitance value of theoscillation capacitor 252. When the resistance value of theoscillation resistor 251 is indicated by RT [kΩ] and the capacitance value of theoscillation capacitor 252 is indicated by CT [μF], the oscillation frequency fOSC [kHz] of theoscillator 250 is given by: -
- In
FIG. 2B , the oscillation signal of theoscillator 250 is denoted by an arrow A, and the oscillation period of the oscillation signal of theoscillator 250 is denoted by a bi-directional arrow B. - The
comparator 253 compares an inverted voltage of the oscillation signal of theoscillator 250 with a reference voltage Vc denoted by an arrow C inFIG. 2B . The T flip-flop 255 outputs a toggle signal in accordance with a signal output from thecomparator 253. Thefirst transistor 258 a and thesecond transistor 258 b output signals via the first output terminal OUTPUT1 and the second output terminal OUTPUT2, respectively, in accordance with signals output from thecomparator 253 and the T flip-flop 255 and an output control signal. InFIG. 2B , an arrow D and an arrow E denote the signals output via the first output terminal OUTPUT1 and the second output terminal OUTPUT2, respectively. In the PWM-control drive circuit 25, the periods in which thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 are turned on are set equal to each other. - The ratio of the magnitude of a voltage Vin input to the DC-to-
DC converter 100 versus the magnitude of a voltage Vout output therefrom is determined by the turns ratio of thetransformer 10 and the duty ratio of the signals output from the first output terminal OUTPUT1 and the second output terminal OUTPUT2. The larger the turns ratio of the primary winding versus the secondary winding of thetransformer 10 becomes, and the lower the voltage output from thetransformer 10 becomes compared with the voltage input thereto, the lower the output voltage Vout becomes. Also, the smaller the duty ratio of the signal output from the first output terminal OUTPUT1 versus the signal output from the second output terminal OUTPUT2 becomes, and the smaller the periods in which thefirst switch 11, thesecond switch 12, thethird switch 13, and thefourth switch 14 are turned on become, the lower the output voltage Vout becomes. - In the DC-to-
DC converter 100, since the primary winding and the secondary winding of thetransformer 10 are isolated from each other, it is possible to isolate the input side and the output side. Also, in the DC-to-DC converter 100, by changing the duty ratio of the signal output from the first output terminal OUTPUT1 and the signal output from the second output terminal OUTPUT2, it is possible to easily change the magnitude of the output voltage Vout. - The DC-to-
DC converter 100, however, suffers from a problem in that it is not easy to reduce the power consumption at light load, since the oscillation frequency of theoscillator 250 does not vary regardless of the magnitude of current flowing in a load coupled to an output end. Power semiconductor devices, such as thefirst switch 11, thesecond switch 12, thethird switch 13, thefourth switch 14, thefirst diode 21, and thesecond diode 22, in the DC-to-DC converter 100 are designed so as to suppress the power consumption at heavy load. That is, those power semiconductor devices are configured with large-size transistors so that the resistance loss, commonly represented by I2R, decreases. However, when the power semiconductor devices are configured with large-size transistors, the parasitic capacitances of the transistors increase and the capacitance loss, commonly represented by CV2f, increases. - In the DC-to-
DC converter 100, when the load current is relatively large, for example, larger than or equal to 50% of a rated load current, and resistance loss among multiple types of loss in the power semiconductor devices is dominant, it is possible to reduce the power consumption. The DC-to-DC converter 100, however, has a problem in that it is not easy to reduce the power consumption when the load current is relatively small, for example, smaller than 50% of the rated load current, and the capacitance loss among losses of the power semiconductor devices is dominant. -
FIG. 3 is a circuit block diagram of a DC-to-DC converter according to a first embodiment. - A DC-to-
DC converter 1 according to the first embodiment is different from the above-described DC-to-DC converter 100 in that the DC-to-DC converter 1 includes a PWM-control drive circuit 30 instead of the PWM-control drive circuit 25. The DC-to-DC converter 1 is also different from the DC-to-DC converter 100 in that the DC-to-DC converter 1 includes a load-current detecting circuit 31 and a switching-frequency switching circuit 32. -
FIG. 4A is an internal-circuit block diagram of the PWM-control drive circuit 30, andFIG. 4B is a circuit block diagram depicting a coupling relationship between the PWM-control drive circuit 30 and the switching-frequency switching circuit 32.FIG. 5 is a timing chart of the DC-to-DC converter 1. - The PWM-
control drive circuit 30 is different from the PWM-control drive circuit 25 in thatconnection terminals frequency switching circuit 32 are arranged between terminals of theoscillation resistor 251. - The load-
current detecting circuit 31 has a load-current detecting resistor 311 and a load-current converter 312. One end of the load-current detecting resistor 311 is coupled toinductors current detecting resistor 311 is coupled to an output terminal. The load-current converter 312 detects the magnitude of a voltage drop Vload due to load current flowing in the load-current detecting resistor 311, and outputs a load-current signal corresponding to the voltage drop Vload due to the load current. - The switching-
frequency switching circuit 32 has a load-current detector 320, aswitch driver 321, aswitch 322, and asecond oscillation resistor 323. The load-current detector 320 includes acomparator 324 that compares the magnitude of the voltage drop Vload due to the load current with a reference voltage Vref. When the voltage drop Vload due to the load current is larger than the reference voltage Vref, thecomparator 324 outputs “1”. Also, when the magnitude of the voltage drop Vload due to the load current is smaller than the reference voltage Vref, thecomparator 324 outputs “0”. In one example, the reference voltage Vref may be set to have a magnitude corresponding to the voltage drop Vload when 50% of a rated current flows in the load-current detecting resistor 311. Theswitch driver 321 turns on or off theswitch 322 in accordance with the signal output from thecomparator 324. Theswitch driver 321 turns on theswitch 322 when “1” is output from thecomparator 324, and turns off theswitch 322 when “0” is output from thecomparator 324. Thesecond oscillation resistor 323, together with theswitch 322 coupled in series therewith, is coupled in parallel with theoscillation resistor 251 in the PWM-control drive circuit 25 via theconnection terminals second oscillation resistor 323 is indicated by RT2. - When the magnitude of the voltage drop Vload due to the load current is smaller than the reference voltage Vref, the
switch 322 is turned off, and thus thesecond oscillation resistor 323 is not coupled to theoscillator 250. In this case, the oscillation frequency fOSC [kHz] of theoscillator 250 is given by: -
- On the other hand, when the magnitude of the voltage drop Vload due to the load current is larger than the reference voltage Vref, the
switch 322 is turned on. When theswitch 322 is turned on, thesecond oscillation resistor 323, together with theoscillation resistor 251, is coupled to theoscillator 250. In this case, the oscillation frequency fOSC [kHz] of theoscillator 250 is given by: -
- where RT′ indicates a resistance value given by:
-
- In the DC-to-
DC converter 1, the resistance value RT of theoscillation resistor 251 and the resistance value RT2 of thesecond oscillation resistor 323 are defined to thereby define the ratio of the oscillation frequency fOSC of theoscillator 250 when the load current is small versus the oscillation frequency fOSC when the load current is large. For example, if the oscillation frequency fOSC given by equation (3) is 100 [kHz], and the resistance value RT2 of thesecond oscillation resistor 323 is 4RT, that is, four times the resistance value RT of theoscillation resistor 251, then the oscillation frequency fOSC given by equation (2) is 80 [kHz]. - In the DC-to-
DC converter 1, when the load current is small, the oscillation frequency fOSC of theoscillator 250 is made to be smaller than that when the load current is large, to reduce the capacitance loss at low load. This makes it possible to reduce the power consumption. In the DC-to-DC converter 1, however, in order to cause theoscillator 250 to operate at two oscillation frequencies fOSC, a relatively large transformer is used as thetransformer 10. -
FIG. 6A is a timing chart illustrating switching of the oscillation frequency fOSC of theoscillator 250, andFIG. 6B illustrates a B-H curve of thetransformer 10 which corresponds toFIG. 6A . InFIG. 6A , the oscillation frequency fOSC of theoscillator 250, which has been 100 [kHz], is switched to 80 [kHz], upon a decrease in the magnitude of the load current. - When the oscillation frequency fOSC of the
oscillator 250 is 100 [kHz], thetransformer 10 transitions within a region denoted by arrows A and B inFIG. 6B , and thus there is no possibility of magnetic saturation. However, when the load current decreases, and the oscillation frequency fOSC of theoscillator 250 is switched from 100 [kHz] to 80 [kHz], the wavelength increases as the frequency decreases. The length of an on period Ton in which thefirst switch 11 and thefourth switch 14 are turned on and the length of an on period Ton in which thesecond switch 12 and thethird switch 13 are turned on increase in proportion to an increase in the wavelength. For example, when the oscillation frequency fOSC of theoscillator 250 is switched from 100 [kHz] to 80 [kHz], and a wavelength TS becomes 1.2 times longer, the on period Ton also becomes 1.2 times longer. - In the DC-to-
DC converter 1, when the oscillation frequency fOSC of theoscillator 250 is switched so as to decrease, and the on period Ton increases, the magnetic flux becomes unbalanced. Consequently, there is a possibility that magnetic saturation occurs in the first quadrant, as illustrated inFIG. 6B . When magnetic saturation occurs, excessive current flows to the first tofourth switches 11 to 14, causing a deterioration of the performance of the first tofourth switches 11 to 14, which may result in breakage of the first tofourth switches 11 to 14. A large-size transformer is used as thetransformer 10 in the DC-to-DC converter 1 so as to ensure that thetransformer 10 is not magnetically saturated even when the oscillation frequency fOSC of theoscillator 250 is switched to reduce the period in which the first tofourth switches 11 to 14 are switched. -
FIG. 7 is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a second embodiment. - A DC-to-
DC converter 2 is different from the DC-to-DC converter 1 in that a switching-frequency switching circuit 42 is provided instead of the switching-frequency switching circuit 32. - The switching-
frequency switching circuit 42 is different from the switching-frequency switching circuit 32 in that aswitch driver 421 is provided instead of theswitch driver 321. The switching-frequency switching circuit 42 is also different from the switching-frequency switching circuit 32 in that aswitch 422 is provided instead of theswitch 322. The switching-frequency switching circuit 42 is also different from the switching-frequency switching circuit 32 in that the switching-frequency switching circuit 42 has afirst switch resistor 423, asecond switch resistor 424, and aswitch capacitor 425. - The
switch driver 421 has adrive switch 426. Thedrive switch 426 is an nMOS transistor and is turned on or off in accordance with a signal output from the load-current detector 320. A gate of thedrive switch 426 is coupled to an output terminal of the load-current detector 320, a source of thedrive switch 426 is coupled to ground, and a drain of thedrive switch 426 is coupled to one end of thefirst switch resistor 423 and thesecond switch resistor 424. - The
switch 422 is an nMOS transistor and is turned on or off in accordance with the on or off state of thedrive switch 426. A gate of theswitch 422 is coupled to a power-supply voltage VCC via thefirst switch resistor 423 and thesecond switch resistor 424 and is coupled to ground via theswitch capacitor 425. When thedrive switch 426 is turned on, a voltage at the gate of theswitch 422 falls from the power-supply voltage VCC to a ground level in a fall time Tf corresponding to a time constant τf determined by the magnitude of a resistance value Rs1 of thefirst switch resistor 423 and the magnitude of a capacitance value Cs1 of theswitch capacitor 425. When thedrive switch 426 is turned off, the voltage at the gate of theswitch 422 rises from the ground level to the power-supply voltage VCC. A rise time Tr corresponds to a time constant τr determined by the magnitudes of the resistance value Rs1 of thefirst switch resistor 423, a resistance value Rs2 of thesecond switch resistor 424, and the capacitance value Cs1 of theswitch capacitor 425. -
FIG. 8A is a timing chart of the DC-to-DC converter 2,FIG. 8B is a partially enlarged chart of a portion denoted by a dashed-line ellipse A inFIG. 8A , andFIG. 8C is a partially enlarged chart of a portion denoted by a dashed-line ellipse B inFIG. 8A . - In the DC-to-
DC converter 2, the rise time Tr of the voltage at the gate of theswitch 422 increases according to the time constant τr. When the rise time Tr of the voltage at the gate of theswitch 422 increases, the length of a region (indicated by an arrow C inFIG. 8B ) in which theswitch 422 performs an active operation increases, and theswitch 422 is turned on gradually. In the DC-to-DC converter 2, since theswitch 422 is turned on gradually, the oscillation frequency fOSC changes gradually from 80 [kHz] to 100 [kHz]. - In the DC-to-
DC converter 2, the fall time Tf of the voltage at the gate of theswitch 422 increases according to the time constant τf. When the fall time Tf of the voltage at the gate of theswitch 422 increases, the length of a region (indicated by an arrow D inFIG. 8B ) in which theswitch 422 performs an active operation increases, and theswitch 422 is turned off gradually. In the DC-to-DC converter 2, since theswitch 422 is turned off gradually, the oscillation frequency fOSC changes gradually from 100 [kHz] to 80 [kHz]. -
FIG. 9A is a timing chart illustrating switching of the oscillation frequency fOSC of theoscillator 250 in the DC-to-DC converter 2, andFIG. 9B illustrates a B-H curve of thetransformer 10 which corresponds toFIG. 9A . - Solid-line arrows in
FIG. 9B indicate characteristics when the oscillation frequency fOSC of theoscillator 250 is 100 [kHz], and a dashed-line arrow indicates a characteristic when the oscillation frequency fOSC of theoscillator 250 is 80 [kHz]. Dashed-dotted line arrows indicate characteristics when the oscillation frequency fOSC of theoscillator 250 transiently reaches 90 [kHz] while it decreases from 100 [kHz] to 80 [kHz]. - In the DC-to-
DC converter 2, when the oscillation frequency fOSC is switched from 100 [kHz] to 80 [kHz], the oscillation frequency fOSC changes gradually, and thus it is possible to switch an operation on the B-H curve while maintaining a symmetry operation at the center point without occurrence of a magnetic flux imbalance. In the DC-to-DC converter 2, since it is possible to switch the operation on the B-H curve while maintaining the symmetry operation at the center point without occurrence of a magnetic flux imbalance, the possibility that magnetic saturation like that described above with reference toFIG. 6B is low. In one example, the time constant τf may be set so that the fall time Tf of the voltage at the gate of theswitch 422 during switching the oscillation frequency fOSC from 100 [kHz] to 80 [kHz] is about 100 times the period of the oscillation frequency fOSC. -
FIG. 10 is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a third embodiment. - A DC-to-
DC converter 3 is different from the DC-to-DC converter 2 in that a switching-frequency switching circuit 52 is provided instead of the switching-frequency switching circuit 42. - The switching-
frequency switching circuit 52 is different from the switching-frequency switching circuit 42 in that adiode 520 is provided parallel to thefirst switch resistor 423. Thediode 520 is provided so that a forward bias is applied when theswitch capacitor 425 is charged and a reverse bias is applied when electricity in theswitch capacitor 425 is discharged. - In the switching-
frequency switching circuit 52, when thedrive switch 426 is turned off and the voltage at the gate of theswitch 422 rises, theswitch capacitor 425 is charged via thediode 520, so that the rise time Tr becomes relatively short. On the other hand, when thedrive switch 426 is turned on and the voltage at the gate of theswitch 422 falls, theswitch capacitor 425 is charged via thefirst switch resistor 423, so that the voltage at the gate of theswitch 422 falls at the fall time Tf corresponding to the time constant τf. -
FIG. 11A is a timing chart of the DC-to-DC converter 3,FIG. 11B is a partially enlarged chart of a portion indicated by a dashed-line ellipse A inFIG. 11A , andFIG. 11C is a partially enlarged chart of a portion indicated by a dashed-line ellipse B inFIG. 11A . - In the DC-to-
DC converter 3, when the voltage at the gate of theswitch 422 rises, current flows via thediode 520, so that the rise time Tr decreases. On the other hand, the fall time Tf of the voltage at the gate of theswitch 422 increases according to the time constant τf. - When the voltage at the gate of the
switch 422 rises, that is, when the oscillation frequency fOSC of theoscillator 250 increases, the magnetic flux density in thetransformer 10 decreases. Thus, there is no possibility of occurrence of the magnetic saturation phenomenon. In the DC-to-DC converter 3, setting the rise time to be relatively short when the voltage at the gate of theswitch 422 rises allows the frequency to be changed from a low frequency to a high frequency. Thus, compared with the DC-to-DC converter 2, the power conversion efficiency improves. -
FIG. 12A is a circuit block diagram illustrating a coupling relationship between a PWM-control drive circuit and a switching-frequency switching circuit in a DC-to-DC converter according to a fourth embodiment, andFIG. 12B is an internal circuit block diagram of a variable resistor inFIG. 12A . - A DC-to-DC converter 4 is different from the DC-to-
DC converter 1 in that a switching-frequency switching circuit 62 is provided instead of the switching-frequency switching circuit 32. - The switching-
frequency switching circuit 62 is different from the switching-frequency switching circuit 32 in that avariable resistor driver 621 is provided instead of theswitch driver 321. The switching-frequency switching circuit 62 is also different from the switching-frequency switching circuit 32 in that avariable resistor 622 is provided instead of theswitch 322. As illustrated inFIG. 12B , thevariable resistor 622 hasnMOS transistors 623 andresistors 624 coupled in parallel. - When a signal input from the load-
current detector 320 changes from “0” to “1”, thevariable resistor driver 621 decides that the load current is larger than a predetermined threshold, and simultaneously turns on some of thenMOS transistors 623. When thevariable resistor driver 621 turns on some of thenMOS transistors 623, the resistance value of thevariable resistor 622 decreases, and the oscillation frequency fOSC of theoscillator 250 increases. Also, when a signal input from the load-current detector 320 changes from “1” to “0”, thevariable resistor driver 621 decides that the load current becomes smaller than the predetermined threshold and turns off some of thenMOS transistors 623. When thevariable resistor driver 621 turns off some of thenMOS transistors 623, the resistance value of thevariable resistor 622 increases, and the oscillation frequency fOSC of theoscillator 250 decreases. - In the DC-to-
DC converters 1 to 4, when the magnitude of the load current detected by the load-current detecting circuit 31 becomes smaller than the predetermined threshold, the oscillation frequency fOSC of theoscillator 250 is switched from a first frequency to a second frequency lower than the first frequency. Also, in the DC-to-DC converters 1 to 4, when the magnitude of the load current detected by the load-current detecting circuit 31 becomes larger than the predetermined threshold, the oscillation frequency fOSC of theoscillator 250 is switched from the second frequency to the first frequency. In the DC-to-DC converters 1 to 4, since the oscillation frequency fOSC of theoscillator 250 at light load decreases, it is possible to reduce capacitance loss that occurs in thefirst switch 11, thesecond switch 12, thethird switch 13, thefourth switch 14, and so on at light load. - Also, in the DC-to-
DC converters 2 to 4, the oscillation frequency fOSC of theoscillator 250 is gradually changed when the oscillation frequency fOSC of theoscillator 250 is switched from the first frequency to the second frequency lower than the first frequency. In the DC-to-DC converters 2 to 4, when the oscillation frequency fOSC of theoscillator 250 is reduced, it is possible to inhibit occurrence of the magnetic saturation phenomenon due to the magnetic flux imbalance in thetransformer 10, by gradually changing the oscillation frequency fOSC of theoscillator 250. - Also, in the DC-to-
DC converters 3 and 4, when the oscillation frequency fOSC of theoscillator 250 is returned from the second frequency lower than the first frequency to the first frequency, the oscillation frequency fOSC of theoscillator 250 is quickly changed. In the DC-to-DC converters 3 and 4, quickly changing the oscillation frequency fOSC of theoscillator 250 when the oscillation frequency fOSC of theoscillator 250 is increased makes it possible to improve the power conversion efficiency, compared with the DC-to-DC converter 2. - Although the DC-to-
DC converters 1 to 4 are configured with hardware, such as transistors, the switching-frequency switching circuits in the DC-to-DC converters 1 to 4 may be partly or entirely realized with software. In one example, thevariable resistor driver 621 in the DC-to-DC converter 4 may have an arithmetic unit that executes various types of processing and a storage unit that stores therein a program for the arithmetic unit to execute the processing and data that the arithmetic unit uses to execute the program. -
FIG. 13 is a flowchart illustrating an example of processing executed by thevariable resistor driver 621 in the DC-to-DC converter 4, andFIG. 14 is a flowchart illustrating another example of the processing executed by thevariable resistor driver 621 in the DC-to-DC converter 4.FIG. 15 is a flowchart illustrating yet another example of the processing executed by thevariable resistor driver 621 in the DC-to-DC converter 4. - In the example processing illustrated in
FIG. 13 , first, in step S101, thevariable resistor driver 621 obtains, from the load-current detector 320, the current value of load current. Next, in step S102, thevariable resistor driver 621 compares the magnitude of the obtained load current with a threshold. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is larger than the threshold, the process proceeds to step S103. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is not larger than the threshold, the process proceeds to step S105. - If the process proceeds to step S103, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. In one example, the first frequency is 100 [kHz]. If thevariable resistor driver 621 determines in step S103 that the present frequency is the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S103 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the process proceeds to step S104. In one example, the second frequency is 80 [kHz]. Next, in step S104, thevariable resistor driver 621 reduces the resistance value of thevariable resistor 622 to change the frequency from the second frequency to the first frequency. - If the process proceeds to step S105, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. If thevariable resistor driver 621 determines in step S105 that the present frequency is the first frequency, the process proceeds to step S106. Next, in step S106, thevariable resistor driver 621 increases the resistance value of thevariable resistor 622 to change the frequency from the first frequency to the second frequency. If thevariable resistor driver 621 determines in step S105 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the processing ends. - In the example processing illustrated in
FIG. 14 , first, in step S201, thevariable resistor driver 621 obtains, from the load-current detector 320, the current value of load current. Next, in step S202, thevariable resistor driver 621 compares the magnitude of the obtained load current with a threshold. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is larger than the threshold, the process proceeds to step S203. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is not larger than the threshold, the process proceeds to step S207. - If the process proceeds to step S203, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. If thevariable resistor driver 621 determines in step S203 that the present frequency is the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S203 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the process proceeds to step S204. In step S204, thevariable resistor driver 621 waits for a predetermined time. Next, in step S205, thevariable resistor driver 621 reduces the resistance value of thevariable resistor 622 by a predetermined amount. Next, in step S206, thevariable resistor driver 621 determines whether or not the resistance value of thevariable resistor 622 is a resistance value for the first frequency. If thevariable resistor driver 621 determines in step S206 that the resistance value of thevariable resistor 622 is a resistance value for the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S206 that the resistance value of thevariable resistor 622 is not a resistance value for the first frequency, the process returns to step S204. - If the process proceeds to step S207, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. If thevariable resistor driver 621 determines in step S207 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S207 that the present frequency is the first frequency, the process proceeds to step S208. In step S208, thevariable resistor driver 621 waits for a predetermined time. Next, in step S209, thevariable resistor driver 621 increases the resistance value of thevariable resistor 622 by a predetermined amount. Next, in step S210, thevariable resistor driver 621 determines whether or not the resistance value of thevariable resistor 622 is a resistance value for the second frequency. If thevariable resistor driver 621 determines in step S210 that resistance value of thevariable resistor 622 is a resistance value for the second frequency, the processing ends. If thevariable resistor driver 621 determines in step S210 that the resistance value of thevariable resistor 622 is not a resistance value for the second frequency, the process returns to step S208. - In the example processing illustrated in
FIG. 15 , first, in step S301, thevariable resistor driver 621 obtains, from the load-current detector 320, the current value of load current. Next, in step S302, thevariable resistor driver 621 compares the magnitude of the obtained load current with a threshold. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is larger than the threshold, the process proceeds to step S303. If thevariable resistor driver 621 determines that the magnitude of the obtained load current is not larger than the threshold, the process proceeds to step S305. - If the process proceeds to step S303, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. If thevariable resistor driver 621 determines in step S303 that the present frequency is the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S303 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the process proceeds to step S304. In step S304, thevariable resistor driver 621 reduces the resistance value of thevariable resistor 622 to change the frequency from the second frequency to the first frequency. - If the process proceeds to step S305, the
variable resistor driver 621 determines whether or not the present frequency is the first frequency. If thevariable resistor driver 621 determines in step S305 that the present frequency is not the first frequency and is the second frequency lower than the first frequency, the processing ends. If thevariable resistor driver 621 determines in step S305 that the present frequency is the first frequency, the process proceeds to step S306. In step S306, thevariable resistor driver 621 waits for a predetermined time. Next, in step S307, thevariable resistor driver 621 increases the resistance value of thevariable resistor 622 by a predetermined amount. Next, in step S308, thevariable resistor driver 621 determines whether or not the resistance value of thevariable resistor 622 is a resistance value for the second frequency. If thevariable resistor driver 621 determines in step S308 that the resistance value of thevariable resistor 622 is a resistance value for the second frequency, the processing ends. If thevariable resistor driver 621 determines in step S308 that the resistance value of thevariable resistor 622 is not a resistance value for the second frequency, the process returns to step S306. - All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Claims (4)
1. A direct current to direct current converter comprising:
a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side;
a switch configured to periodically switch the voltage applied to the first side of the transformer;
a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and
a switching-frequency switching circuit configured to switch,
when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch,
when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.
2. The direct current to direct current converter according to claim 1 ,
wherein, during the switching of the frequency for switching the switch from the first frequency to the second frequency lower than the first frequency, the switching-frequency switching circuit gradually reduces the frequency.
3. The direct current to direct current converter according to claim 2 ,
wherein a transition time in which the frequency for switching the switch from the first frequency to the second frequency is longer than a transition time in which the frequency for switching the switch is switched from the second frequency to the first frequency.
4. The direct current to direct current converter according to claim 1 ,
wherein the switch comprises a plurality of metal oxide semiconductor transistors.
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JP2013214968A JP6171825B2 (en) | 2013-10-15 | 2013-10-15 | DC / DC converter |
JP2013-214968 | 2013-10-15 |
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US20150103565A1 true US20150103565A1 (en) | 2015-04-16 |
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US14/510,524 Abandoned US20150103565A1 (en) | 2013-10-15 | 2014-10-09 | Dc-to-dc converter |
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JP (1) | JP6171825B2 (en) |
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US9590615B1 (en) * | 2015-09-18 | 2017-03-07 | Sanken Electric Co., Ltd. | Integrated circuit and switching power-supply device performing output control through switching operation |
US10439500B2 (en) | 2017-02-01 | 2019-10-08 | Infineon Technologies Austria Ag | Control of isolated power converters during transient load conditions |
US10554138B2 (en) | 2016-10-25 | 2020-02-04 | Infineon Technologies Austria Ag | Flux limited fast transient response in isolated DC-DC converters |
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JP2717913B2 (en) * | 1992-12-25 | 1998-02-25 | 東洋電機製造株式会社 | Switching frequency control method |
JP2814917B2 (en) * | 1993-06-07 | 1998-10-27 | 日本電気株式会社 | Switching power supply circuit |
JPH0851774A (en) * | 1994-08-08 | 1996-02-20 | Nec Corp | Switching power supply circuit |
JPH09117134A (en) * | 1995-10-17 | 1997-05-02 | Murata Mfg Co Ltd | Switching power supply |
JP4285041B2 (en) * | 2003-03-28 | 2009-06-24 | ソニー株式会社 | Switching power supply |
JP2007068349A (en) * | 2005-08-31 | 2007-03-15 | Tdk Corp | Switching power supply |
JP4811102B2 (en) * | 2006-04-26 | 2011-11-09 | 日産自動車株式会社 | Control device and control method for power conversion device |
JP4120694B1 (en) * | 2007-01-09 | 2008-07-16 | ダイキン工業株式会社 | Inverter compressor operation method and compressor drive device |
US7928712B1 (en) * | 2007-06-01 | 2011-04-19 | Rf Micro Devices, Inc. | Low noise fast dithering switching power supply |
JP5121517B2 (en) * | 2008-03-18 | 2013-01-16 | 三菱電機株式会社 | Discharge lamp lighting device, lighting device |
JP5566655B2 (en) * | 2009-10-07 | 2014-08-06 | 新電元工業株式会社 | Switching power supply |
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2013
- 2013-10-15 JP JP2013214968A patent/JP6171825B2/en active Active
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2014
- 2014-10-09 TW TW103135187A patent/TW201526507A/en unknown
- 2014-10-09 US US14/510,524 patent/US20150103565A1/en not_active Abandoned
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US20080061759A1 (en) * | 2006-09-12 | 2008-03-13 | O2Micro Inc. | Power supply topologies with pwm frequency control |
US20120163037A1 (en) * | 2010-12-24 | 2012-06-28 | Samsung Electro-Mechanics Co., Ltd. | Resonant converter |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
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US9590615B1 (en) * | 2015-09-18 | 2017-03-07 | Sanken Electric Co., Ltd. | Integrated circuit and switching power-supply device performing output control through switching operation |
US20170085259A1 (en) * | 2015-09-18 | 2017-03-23 | Sanken Electric Co., Ltd. | Integrated circuit and switching power-supply device performing output control through switching operation |
US10554138B2 (en) | 2016-10-25 | 2020-02-04 | Infineon Technologies Austria Ag | Flux limited fast transient response in isolated DC-DC converters |
DE102017124966B4 (en) | 2016-10-25 | 2023-06-29 | Infineon Technologies Austria Ag | Flux-limited fast transient response in isolated DC-DC converters |
US10439500B2 (en) | 2017-02-01 | 2019-10-08 | Infineon Technologies Austria Ag | Control of isolated power converters during transient load conditions |
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JP6171825B2 (en) | 2017-08-02 |
JP2015080303A (en) | 2015-04-23 |
TW201526507A (en) | 2015-07-01 |
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